Reporting in the Jan 27. issue of the journal Circulation, University of Pennsylvania researchers found that adherence to medication dropped more than 19 percent among veterans who had to make co-payments when that amount was increased in 2002. By comparison, medication adherence dropped by only 12 percent among veterans who were exempt from co-pays.

In addition, the odds of being without medication for more than three months was three times higher during this time among veterans who had to make co-pays than among those exempt from the payments, the study found.

"This decline in adherence was not just a result of short gaps in use interspersed between prescription refills," said Jalpa A. Doshi, a research assistant professor of medicine at the University of Pennsylvania and lead author of the study. "In fact, the co-payment increase was accompanied by a significant increase in the likelihood of having continuous gaps of 90 days or more in lipid-lowering medication use."

The finding is of particular importance today, Doshi indicated, because of efforts being made to save federal dollars.

"In this era of large federal budget deficits, it is clear that there will be ongoing pressure to reduce or at least constrain growth of the VA budget, and one of the approaches that the Congress may take to cut costs is through increases in VA prescription co-payments," Doshi said. The study looked at what happened when co-pay amounts were increased earlier this decade.

In 2002, it found, many veterans went without needed medication after the VA (Department of Veterans Affairs) raised co-payments from $2 to $7 for a month's supply of a prescription drug.

The co-pay amount was increased again in 2006, to $8, Doshi said. And several presidential budget proposals, including the 2008 plan, included a co-payment increase to $15 for a 30-day supply, she said.

"While these proposals were not incorporated into legislation, it is likely they might be in the future," Doshi said. "Policymakers must consider the findings and implication of studies such as ours in future policy reform initiatives."

Co-pay amounts are the same whether a drug is a generic or a brand-name medication, she said.

"This is particularly relevant in the case of cholesterol-lowering medications such as statins, wherein two brand-name statins have become available as generics since 2006 and are available at significantly lower prices to the Department of Veterans Affairs," Doshi said "Presumably, the VA could charge veterans lower co-payments for such medications and thereby facilitate higher adherence with drugs from such essential medication classes."

For the study, Doshi and her fellow researchers collected data on 5,604 veterans taking cholesterol-lowering drugs prescribed by the Philadelphia VA Medical Center from November 1999 to April 2004.

They compared veterans who had to make co-payments with similar veterans who were exempt from prescription drug co-payments, and they looked at adherence to cholesterol-lowering drugs in the two years before and the two years after the co-pay increase.

Besides the overall drop in adherence rates, the researchers detected a decline among a particular group of veterans.

"Of even greater concern was our finding that a similar adverse effect of the co-payment increase was observed in groups at higher risk for coronary heart disease who were using these medications for either primary or secondary prevention," Doshi said.

Because of this, she said, "policymakers need to pay particular attention to the fact that a 'one-size-fits-all' approach to designing cost-sharing policies may adversely affect certain higher-risk patients."

As an alternative to an across-the-board increase, Doshi suggested linking co-payments to individual needs: "specifically, lower patient co-payments for higher expected therapeutic benefit and higher co-payments for lower therapeutic benefit." She called that idea "a more promising approach."

Dr. Steffie Woolhandler, an associate professor of medicine at Harvard Medical School, said she thinks the study highlights the need for reform that would make medical treatment and medication available to all.

"This paper provides striking evidence that co-payments for medications are potentially lethal," Woolhandler said. "Even a seemingly modest increase in the cost of vital medications discourages many patients from taking medications that we know prevent heart attacks and strokes."

The finding "adds further evidence that Americans need full coverage, without co-payments or deductibles, if we are to realize the full promise of today's medical advances," she stressed.